We are exploiting the utility of C. elegans and other model systems in studying conserved nutrient signalling pathways. In collaboration with Iqbal Hamza's group (Univ of Maryland), we have continued to study how heme levels are sensed and regulated in animals using model systems that provides unique advantages. During the past year, we completed a study of the heme-regulated gene number one (Hrg1)that plays a role in organismal heme homeostasis. Using the zebrafish system, the Hamza group performed developmental and biochemical analyses that demonstrated a role for Hrg1 in heme-iron recycling during hemolysis in the kidney, aided by our bioinformatic analysis of RNA-seq data from animals lacking both hrg-1 paralogs. These results established the zebrafish kidney as the major organ for red blood cell recycling and identify Hrg1 as an important regulator of heme-iron recovery by macrophages.